Powder coatings are solvent-free, 100% solids coating systems that have been used as low VOC alternatives to traditional liquid coatings and paints.
Powder coating of metal parts is a common practice. It is difficult, however, to coat certain parts of a metal substrate, including edges and corners, for example, to obtain a uniform coating using typical powder coating processes. Consequently, edge corrosion is a common problem. Typically, when powder coatings are applied to metal parts, a low-flow coating which provides good edge coverage is used. However, such coatings have a tendency to produce wavy surfaces characterized as orange peel, or surfaces with raised grains, i.e. surfaces with low smoothness. On the other hand, when flow is increased to provide greater smoothness, edge coverage thins, and may fail altogether; leaving metal parts prone to edge corrosion. Conventional systems that attempt to combine flow characteristics with increased surface smoothness typically require multiple application and heating steps, leading to process inefficiency and delay.
From the foregoing, it will be appreciated that there is a need for effective powder coating of metal parts, where multiple cure cycles are eliminated, and where the coating demonstrates excellent performance characteristics, such as excellent corrosion protection, including at the edges, and optimal surface smoothness.